Loading or transfer systems for fluids



Oct. 17, 1967 w. lTH 3,347,286

LOADING OR TRANSFER SYSTEMS FOR FLUIDS Filed May 18, 1964 LAWRENCE w.SMITH,

, INVENTOR.

L/MTW ATTORNEY United States Patent Filed May 18, 1964, Ser. No. 368,0328 Claims. (Cl. 141--39) This invention relates to loading or transfersystems for fluids, particularly vaporizable liquids such as liquefiedperoleum gas (LPG).

A present conventional system will first be described and then thenature and advantages of the present invention will be set forth.

Present LPG delivery systems frequently involve the transportion of theLPG, which is customarily mixtures of butane, propane and associatedhydrocarbons in liquefied form, to the delivery site by means of a tanktruck. However, the system may involve the delivery of LPG from astationary storage to a tank which is brought to the storage tank. Thepresent invention is applicable to all such systems.

A typical delivery involves the driving of a tank truck as close asfeasible to the tank of the consumer. Even under optimum conditions,however, this usually represents quite a distance, and as a result aconsiderable length of flexible delivery hose, piping, or other suitableconduit is required to connect between the truck tank and the consumerstank. In a typical operation the operators time and the amortized costof the truck are as much a factor in the total economy of the procedureas is the cost of the LPG itself. Therefore, the quicker the deliverycan be effected, the more effective and efiicient will be the entireoperation. Because of the time factor, and also because operators desireto do no more manual labor than necessary, it is customary for theoperator, after positioning his truck in delivery position, to start thedelivery pump before carrying the delivery hose to the consumers tank.The pump has an input in communication with the truck tank and an outputfeeding a flexible hose, the other end of which is adapted to beconnected to the consumers t-ank. At the output end of the hose there isa shutoff valve which is normally kept closed.

The operator, beforeleaving the site of the truck, starts the pump anddrags the hose over to the consumers tank. He then connects the outputend of the hose to the consumers tank and opens the valve at the outputend of the hose. This starts the filling operation.

In the meantime, however, in the interval between the starting of thepump and the opening of the valve at the output of the hose, which is aconsiderable period of time depending on the distance and the difiicultyof stringing the hose from the truck to the tank, the pump has, ofcourse, beenrunning continuously and building up pressure. Since LPGpumps are usually positive displacement pumps, some means must beprovided to accommodate the pump output during this period. This iscustomarily done by a bypass pipe which leads from the output of thepump back to the truck tank. Interposed in the bypass pipe is a bypassvalve which is usually a spring loaded type valve commonly set to openwhenever the output pressure in the pump discharge line exceeds thepressure in the storage tank by a given amount, for example, 75 poundsper square inch. The bypass valve imposes a pressure differential of atleast 75 pounds per square inch upon the pump.

sures are generally proportioned to As the pressure across the bypassvalve builds up, the valve opens at around lbs., and thereafter operatesso as to maintain a substantially constant pressure differential of 75lbs., at all flow rates.

As a result the bypass activity of the pump during the time that theoperator takes to connect the consumers tank represents a complete wasteof energy and a considerable wear on the pump, since it is workingagainst a maximum pressure while doing no useful work.

After the required quantity of LPG has been pumped into the consumerstank, the operator reverses his procedure. He closes the valve at theoutput end of the hose, reels the hose in as he returns to the truck,and then turns off the pump. This period also represents a completewaste of energy and a period during: which the pump is pumping futilelyagainst maximum pressure.

Another shortcoming of present day filling apparatus is that the buildupof pressure in the consumers tank raises its pressure undesirably, withconsequent limitation on the amount of filling possible. In the usualsituation the consumers tank is relatively empty, that is, filled with asmall amount of liquid and a large: amount of vapor. During the fillingoperation the liquid volume increases, compressing the vapor into asmaller and smaller volume. The resultant heat raises the temperature ofthe con sumers tank and hence increases its pressure. Tank presambienttemperature. Consumer tanks have relief valves set to open atapproximately 250 p.s.i. Except on very hot days, the pressure of thetruck tank, added to the pressure differential setting of the bypassvalve, does not come close to the 250 p.s.i. relief valve setting; yet,as soon as the pump discharge pressure exceeds the sum of truck tankpressure and bypass valve setting, the bypass valve opcns, deliveryceases, and the operator is forced to leave the consumers tank onlypartially filled, even though much more LPG could have been safelydelivered without the relief valve opening. 0n the other hand, on hotdays, the pressure in the consumers tank may, after some liquid istransferred, exceed the blow off pressure at which the relief valveopens, thereby spewing inflammable and/or explosive LPG throughout thearea.

In the past it was customary to connect a vapor return line from thevapor space of the consumers tank back to the delivery tank, to preventbuild up of excess pressure in the former. However, the LPG thusreturned represented an unmetered loss to the consumer, and thispractice has been barred in most states by various consumer-protectivelaws.

It is the object of the present invention to obviate certainshortcomings and disadvantages of the present day tank filling systemand procedure.

It is a further and specific object to provide a system which allows thepump to work against the maximum safe total pressure.

Still more specifically, it is an object of this invention to relievethe load on the pump when the hose valve is closed by providing meansfor opening the bypass valve fully during the connecting anddisconnecting interval, thereby relieving the pump from the heavy loadagainst which it must otherwise work during these intervals.

It is a further object of this invention to provide a system in whichthe consumers tank may be filled up to a safe pressure even on hot days,without the danger of relief valve blow off. At the same time the systempermits use of greater differential pressures where safe, and in coolerweather, with consequent greater filling capacity.

A preferred embodiment of the present invention will now be describedwith reference to the accompanying drawings wherein:

FIG. 1 is a diagram showing the principal elements involved in the tanktruck filling of a consumers tank.

FIG. 2 is a schematic diagram showing in enlarged fashion a portion ofthe hookup betwen the truck tank and the consumers tank which employs aspecial type of valve constructed in accordance with principles of thepresent invention.

FIG. 3 is a detailed cross-sectional view of the s ecial bypass valveillustrated in FIGS. 1 and 2.

In the drawings there is illustrated a system for transferring fluidfrom a first container to a second container. Specifically there isillustrated as the first container a tank 11 which may or may not bemounted on a truck 12 that is to transfer LPG to a consumers tank 13.The vaporizable liquid, for example LPG, is drawn from the tank 11 by apump 14 and thence directed to a flexible conduit or hose 16, the outlet17 of which is connected to the tank 13. A bypass conduit or pipe 15 isconnected from the output of the pump 14 to a special bypass valve 18and thence back to the tank 11, as shown at 19.

The operator, after parking the truck 12 in loading position, preparesto unreel the hose 16 to the tank 13 and there connect it. Before doingso, however, he starts the pump 14, in order that he will not have toreturn to the truck after connetcing the hose 15 to the tank 13. At theoutlet end 17 of the hose 16 is a manually operable valve which is inclosed position. When the pump 14 starts, it rapidly builds upsufiicient pressure so that the pressure differential across the bypassvalve 18 is sufficient to open the valve wide and permit the liquid toreturn directly to the tank through the pipes 1549, under very littlemore pressure that that in tank 11.

In accordance with the present invention, the bypass valve 18 in thebypass or recirculating pipe 15 is designed to respond to pressure inthe tank 13 (or alternatively in the hose 16) in such a way as to moveabruptly from fully closed position to fully open position when thepressure in the tank 13 or in hose 16 exceeds a predetermined value, andto move abruptly from fully open position to fully closed position whenthe pressure in 13 drops below a predetermined value. By this techniquethe pump 14 is not forced to work at high pressure through the bypassvalve 18. Since the valve 18 opens completely in response to a pressurebuildup in the hose 16 or tank 13, there is only insignificant pressuredrop across the valve 18. Thus the pump 14 is able to work against avery low output pressure, only slightly higher than its input pressure(which is the pressure in the tank 11), thereby greatly lessening thedeadweight load on the pump during the connecting and disconnectingoperation.

In accordance with the present invention, this abrupt opening of thevalve 18 is achieved by providing a pressure sensitive means which isindependent of the bypass conduit 15. This pressure sensitive meansactuates the valve 18. Means are provided for applying to this pressuresensitive means a pressure which is the function of the pressure in thetank 13 or hose 16. In a preferred embodiment of the present inventionthe means for applying this pressure takes the form of another flexiblehose 21 and a cross conduit 22. Hose 21 is connected to the vapor spaceof the tank 13 above the liquid level therein. At the free end 20 ofhose 21 is a manually operable valve. The pressure in the hose 21, or inline 22, is applied to a special pressure sensing chamber in the valve18 which serves to initiate actuation of the valve member from open toclosed position and vice versa.

Cross conduit 22 is provided between the output of the pump 14 and theconnection or input 23 to the pressure sensitive compartment or chamberof the valve 18. Interposed between the output of the pump 14 and thecross connection 22 are a conventional check valve 24 which preventsback flow toward the pump 14 and a meter 26 which measures the amount offuel passed into the transfer hose 16. The cross connection 22 alsoincludes an orifice fitting 27 and a check valve 28 which permits fluidto flow (upwardly in FIG. 2) from the output of the pump 14 to thechamber input 23 but not in a reverse direction. A conventional reliefvalve 29 is provided near the input to the pressure sensing portion ofvalve 18. Valve 29 opens to allow escape of fluid should the pressurebecome dangerously high. The orifice 27 may consist of a partiallyclosed valve, and thus be adjustable. The function of orifice 27 is torestrict appreciable flow of fluid from the line 16, so that whenconduit 21 is opened to tank 13 at 241, the valve 18 will not open.

A form of valve 18 suitable for use in the present system is shown inFIG. 3. In this figure the valve casing 31 is provided with a number ofchambers in communication with the valve member 32. There is an inletchamber 33 to which the bypass pipe or conduit 15 is connected. As notedhereinbefore, the input end of the pipe 15 is connected to the output ofthe pump 14. There is an outlet chamber 34 to which the pipe 19, leadingback to the tank 11, is connected. Passage of fluid from the chamber 33to the chamber 34 is controlled by a valve 36 which seats at 37 to blockpassage between the two chambers. Fluid pressure in the inlet chamber 33on the valve 36 is balanced by a piston 38, so that irrespective of thepressure in chamber 33 there will be no net effective force tending tomove the valve member 32 in either direction.

Above the valve 36 is a balancing chamber 41 separated from the chamber34 by an isolating piston 42. Above the chamber 41 and isolatedtherefrom by a transverse wall 43 is a pressure sensitive or actuatingchamber 44. A valve stem 46 passes centrally upward in the valve casing31 and to it is secured the pistons 38, 42 and the valve 36. The stem 46passes through a central opening in the transverse wall 43, an O ring46' serving to maintain fluid isolation between chambers 41 and 44. Onthe rod 46 and closing the chamber 44 is a piston 47.

The entire valve member 32 is mechanically biased downward by acentrally disposed compression spring 48, the lower end of which bearsagainst the piston 47, the upper end being adjustable through anadjusting screw 49 to adjust the downward bias on the valve member 32.

It will be noted that the pressure in the chamber 34 tends to move thevalve member 32 upwardly, the latter being exposed to the chamber 34 notonly in the annulus surrounding the valve 36 but also at the lower endof the valve stem 46 and the bottom portion of the piston 38. Thisupward force is substantially offset by the downward force exertedthrough the pressure in the chamber 41 which bears against the piston42. The chamber 41 is connected by a pipe or other suitable conduit 51back to the vapor space in the tank 11 above the level of the liquidcontained therein. Since liquid and vapor pressures in the tank 11 aresubstantially equal, the pressures in chambers 34 and 41 are likewisesubstantially equal, and hence the net force on the valve member 32 issubstantially zero, departing from Zero only by the slight difference ineffective pressure area accessible to the chamber 41 in relation to thepressure sensitive area accessible to the chamber 34. Any net forcetending to move the valve member 32 upward is more than offset by theadjustable spring 48, which tends to keep the valve closed, with thevalve 36 seated on the seat 37. Actuation of the valve 18 is thusdependent upon the pressure in the chamber 44, which is connected to thepipe 23 leading to the vapor hose 21.

Operation The operation of the LPG transfer and loading system hereindescribed is as follows:

After positioning the truck 12 the operator prepares to unreel the hoses16 and 21 over to the consumers tank '13. Before leaving the truck 12 hestarts the pump 14, which is usually powered from the truck engine.Pressure at the otuput of the pump 14 promptly builds up to a pressureappreciably greater than that in the tank 11. This pressure is conveyedthrough the check valve 24, the meter 26, the orifice fitting 27, andthe check valve 28, to the pipe 23 and thence to the chamber 44. Whenthe pressure becomes large enough to overcome the bias of the spring 48,the force on the piston 47 moves the valve member 32 upward, opening thevalve 36. With the opening of the valve 36 the output of the pump mayfio-w freely through the bypass 15, chambers 33 and 34 and pipe 19, backto the truck tank 11. This abrupt and full opening of the valve 36allows the pressure at the output of the pump 14 to drop markedly and beonly slightly greater than the input pressure to pump 14. Thus the loadon the pump is greatly decreased. The drop in pressure at the output ofthe pump 14 does not affect the pressure in the chamber 44, however,because of the check valve 28.

The operator proceeds to unroll the hoses 16 and 21 and connects them tothe tank 13, the former being connected at 17 to the tank 13, the latterbeing connected to the vapor space of the tank 13 above the level of theLPG therein. The operator thereupon opens the manually operable valves17 and 20 located at the free ends of the hoses 16 and 21, respectively.As soon as the hose 21 is exposed to the vapor pressure in the tank 13,the pressure in the hose 21 drops, thereby dropping the pressure in thechamber 44 and permitting spring 48 to close the valve 36. Thereupon thecontinued operation of the pump -14 forces LPG into the liquid hose 16and thence into the consumers tank 13. As the pressure in the tank 13builds up, it is transmitted through the vapor hose 21 to the chamber44. When the point is finally reached where the tank 13 has maximumsafepressure, the setting of the spring 4-8 is such as to permit thepressure in chamber 44 to again lift the valve 36, opening the bypassconduits 19 and again permitting the pump 14 to work at low loss throughthe bypass and back to the truck tank 11. The operator thereupon closesthe valves at 17 and 20, disconnects the respective hoses, and reelsthem back to the truck. He then shuts off the pump 14, loads up hisequipment and prepares ,to depart.

An alternative arrangement consists of connecting the end 2%) of hose 21to the hose 16 adjacent its end 17. A valve is interposed at the end ofhose 21 immediately before its connection to the hose 16 so that hose 21may be selectively isolated from hose 16. This arrangement has theadvantage of requiring that the operator make only a single pressureconnection to the consumers tank 13, instead of two connections as inthe previously de scribed embodiment.

This alternative embodiment of the invention is used substantially inthe same way as the previously described embodiment. The operatorconnects the hose 16 to the consumers tank 13, opens the valve whichplaces the hose 16 in communication with the tank 13 and then opens thevalve at the end of hose 21 where it joins the hose 16. In thisarrangement the pressure sensed in the vapor hose 21 is a few poundshigher than in the earlier embodiment because of the pressure dropacross the fitting as the fluid flows from the hose 16 into the tank 13.This difference is small, and makes for a more conservative arrangement,for the pressure sensed by the hose 21 then tends to open the bypassvalve 18 even sooner than before as the pressure in the tank 13 buildsup. Thus there is even less.

danger of popping the release valve on the consumers tank 13. Thisarrangement of course is accompanied by the concomitant disadvantagethat the tank 13 would not be filled quite as full as in the firstembodiment.

While the instant invention has been shown and described herein in whatis conceived to be the most practical and preferred embodiments, it isrecognized that departures may be made therefrom within the scope of theinvention which is therefore not to be limited to the details disclosedherein, but is to be afforded the full scope of the invention ashereinafter claimed.

What is claimed is:

1. In a system for transferring fluid from a first container to a secondcontainer and having a transfer conduit between said containers, a pumpin said transfer conduit, and a recirculating bypass from the pumpoutput to said first container, the combination comprising:

a bypass valve in said recirculating conduit, and

means directly connected and responsive to pressure in said secondcontainer for causing said bypass valve to move abruptly from fullyclosed to fully open position when the pressure in said second containerexceeds a predetermined value, and to remain open during recirculationof fluid back to said first container.

2. In a system for transferring fluid from a first container to a secondcontainer and including a transfer conduit, a pump in said transferconduit having its input connected to said first container and itsoutput connected to said second container, a recirculating conduitconnected from the output of said pump to said first container, and abypass valve in said recirculating conduit, the combination comprising:

means independent of said transfer conduit for sensing the pressure insaid second container, and

means responsive to said sensing means for opening said valve when thepressure in said second container exceeds a predetermined amount.

3. In a system for transferring vaporizable liquid from a truck tank toa consumers tank and including a transfer hose, a pump having its inputconnected to the truck tank and its output connected to the transferhose, a recirculating pipe connected from the output of said pump tosaid truck tank, and a bypass valve in said recirculating pipe, thecombination of:

means independent of said transfer hose for sensing the pressure in theconsumers tank, and

means responsive to said pressure for placing and maintaining said valvein open position as long as the pressure in the consumers tank exceeds apredetermined amount.

4. In a system for transferring liquefied gas from a truck tank to aconsumers tank and including a transfer hose, a pump having its inputconnected to the truck tank and its output connected to said transferhose, a recirculating pipe connected from the output of said pump to thetruck tank, and a bypass valve in said recirculating pipe, thecombination comprising:

pressure responsive means for actuating said valve between open andclosed positions,

a vapor hose having one end connected to sure responsive means, theother to being connected to the vapor sumers tank,

a shunt pipe connected between the output of said pump and said pressureresponsive means, and a check valve in said shunt pipe for permittingpassage of fluid from the output of said pump to said pressureresponsive means while blocking passage in the reverse direction,

whereby upon operation of said pump with both of said hoses shut off,pressure will be applied from said pump to said pressure responsivemeans to open said valve and allow bypass circulation from the output ofsaid pump back to said truck tank, and upon connecting of said hoses tothe consumer's tank and opening of said hoses the drop in pressure insaid vapor hose will cause said pressure responsive means to allow saidvalve to close, thereby pumping the output of said pump through saidliquid hose into the consumers tank.

5. In a liquefied petroleum ing a tank truck having a transport tankthereon, a pump having its input connected to said truck tank, atransfer hose connected to the output of said pump, the other saidpresend being adapted space of the congas transfer system includend ofsaid transfer hose being adapted to be connected to a consumers tank, abypass pipe connected from the output of said pump back to said trucktank, and a bypass va'lve in said bypass pipe, said valve having a valvemember for opening and closing fluid flow through said bypass pipe andan actuating member for actuating said valve member, the combinationcomprising:

pressure sensitive chamber means for applying an actuating force to saidactuating member in response to pressure in said chamber,

a vapor hose having one end in communication with said chmaber, theother end of said vapor hose being adapted to communicate with theconsumers tank,

a cross conduit connected between the output of said pump and saidchamber and having therein a check valve for permitting fluid flow fromsaid pump to said chamber but blocking flow in the reverse direction,and flow restricting means to effect pressure drop during fluid flowtherethru,

whereby said valve is actuated in accordance with pressure in saidchamber in order to bypass liquid back to the tank when the pressure insaid chamber eX- ceeds a predetermined value and to close the bypassvalve when the pressure in said chamber drops below a predeterminedvalue.

6. In a system for transferring fluid from a first container to a secondcontainer, and having a transfer conduit between said containers, a pumpin said transfer conduit, and a recirculating by-pass conduit around thepump, the combination comprising:

a by-pass valve having a valve member in said recirculating conduitmovable between open and closed positions,

mechanical bias means urging said valve to closed position,

a first control chamber and a second control chamber, pressure in saidfirst control chamber biasing said valve member to closed position,pressure in said second control chamber tending to cancel saidmechanical bias means thereby biasing said valve member to openposition,

conduit means for connecting said first control chamber with said firstcontainer, and

conduit means for connecting said second control chamber with saidsecond container. 7. System in accordance with claim 6 wherein saidvalve has an inlet chamber connected to the output side of said pump andan outlet chamber connected to the input side of said pump, the pressurein said outlet chamber tending to move said valve member to openposition and the pressure in said inlet chamber having no substantialnet effect on said valve.

8. A control valve comprising: a balanced inlet chamber, an outletchamber, a third chamber and a fourth chamber; a valve member movablebetween open and closed positions, interposed between said inlet andoutlet chambers and adjacent to and in pressure communication with saidthird chamber thereby being responsive to pressure changes in said thirdchamber;

mechanical bias means urging said valve to closed position, adjacent tosaid fourth chamber and responsive to pressure changes therein;

the pressure in said outlet chamber tending to move said valve to openposition, the pressure in said inlet chamber having no substantial neteffect on said valve, the pressure in said third chamber tending to movesaid valve to closed position and the pressure in said fourth chambertending to cancel said mechanical bias means thereby opening said valve.

References Cited UNITED STATES PATENTS 1,901,335 3/1933 Reynolds 141392,018,119 10/1935 Brouse 137115 X 2,421,325 5/1947 Griswold l37115 X2,536,663 1/1951 SChaer 137-115 X 2,690,760 10/1954 Hughes 137484.2

FOREIGN PATENTS 1,298,300 5/1962 France 25162 SAMUEL ROTHBERG, PrimaryExaminer.

E. J. EARLS, Assistant Examiner.

1. IN A SYSTEM FOR TRANSFERRING FLUID FROM A FIRST CONTAINER TO A SECONDCONTAINER AND HAVING A TRANSFER CONDUIT BETWEEN SAID CONTAINERS, A PUMPIN SAID TRANSFER CONDUIT, AND A RECIRCULATING BYPASS FROM THE PUMPOUTPUT TO SAID FIRST CONTAINER, THE COMBINATION COMPRISING: A BYPASSVALVE IN SAID RECIRCULATING CONDUIT, AND MEANS DIRECTLY CONNECTED ANDRESPONSIVE TO PRESSURE IN SAID SECOND CONTAINER FOR CAUSING SAID BYPASSVALVE TO MOVE ABRUPTLY FROM FULLY CLOSED TO FULLY OPEN POSITION WHEN THEPRESSURE IN SAID SECOND CONTAINER EXCEEDS A PREDETERMINED VALUE, AND TOREMAIN OPEN DURING RECIRCULATION OF FLUID BACK TO SAID FIRST CONTAINER.